Discovering deep-sea sharks

Spending weeks in the bowels of a massive fishing vessel dissecting hundreds of sharks in a particularly stormy and remote section of the Southern Indian Ocean requires some motivation. For 29-year-old graduate student Paul Clerkin, the promise of discovering new shark species was a very powerful incentive. In June this year Paul returned from his second 60-day expedition aboard the F/V Will Watch, a 65-metre commercial trawler.

On both trips, Paul first flew from California to the tiny French island of Mauritius, where he met the rest of the crew. From here they travelled 16,000 kilometres south to beyond the island of Madagascar, where submerged mountains rise from the inky depths of extinct undersea volcanoes. These underwater pillars act just as islands would above water, providing critical homes for near-ranging, deep-sea species that are isolated from the wider ocean ecosystem. Because of this, these steeply sloping sea mounts and ridges are hotspots for biodiversity and endemism.

Paul calls the Southern Indian Ocean ‘the last frontier of ocean exploration and discovery’. For hundreds of years, this treacherous and remote section of ocean has remained unfished, unexplored and highly productive. Even today, only a few commercial fishers are brave enough to trawl its waters for deep-dwelling species like orange roughy and alfonsino. When the net is hauled up from two kilometres deep it contains many other alien-like fish, including deep-sea sharks. As the nets are emptied, Paul examines all the sharks caught as by-catch. He then returns the live ones to the sea and carries the dead ones to his workstation, where he identifies them, takes measurements and collects samples for genetic analysis.

From demon catsharks with glowing eyes to purple-finned chimaeras and huge, flabby, torpedo-shaped false catsharks, these are some of the oddest creatures known to science – and many of them weren’t even known before Paul began his research. During his 20 weeks aboard the F/V Will Watch, he discovered an estimated 15 new shark species, including a small sleeper shark – the find that excites him most. Paul already has his sights on another, longer trip when he will spend 100 days at sea in a different area of the Southern Indian Ocean. But before that he has a lot of data that needs to be written into a Master’s thesis, and he will be submitting papers describing two new species of ghost shark.

Cover image

Photo by Discovery Channel

Project

Discovering deep-sea sharks

We know very little about the sharks of the deep. Paul has embarked on two expeditions to the stormy and remote reaches of the Indian Ocean to bring the mysteries of these underwater aliens to the surface.